The biosynthesis and distribution of basic (histones) and acidic (nonhistone) proteins is being studied in chromatin and nuclei of maturing male gametes in mice and rats. Characterization of these proteins includes their phosphorylation, DNA- binding capacity and immunospecificity. Special attention is paid to protamine-like proteins in mature spermatozoa and to the DNA-binding proteins in maturing cells. The DNA binding proteins include both the histones and nonhistone proteins. In another part of this project we are investigating the biochemical nature of DNA restriction and gene regulation in female gametes and during early embryonic development of sea urchins. The nuclear nonhistone proteins are studied in detail with special attention being paid to the nonhistone protein fractions with affinity for the DNA.